Individual Page – Background Heading Image option gone from 'Edit Page'

Hi! Thanks for your amazing support. I have just gone to upload a new background header image into one of my pages, but it appears that the custom background image area has disappeared from the page edit options (at the bottom). Usually, I scroll to the bottom of the Edit Page area, and there is the option to load an alternative header image to the default. I have deactivated the 3 plugins that I recently installed as I thought there might have been a conflict, but the issue still remains. The only other thing that I did recently was update the theme. Has the most recent update removed this option? Could you please take a look for me? Looking forward to hearing from you.